Control of convertible evaporatorcondensers for use in refrigerative circuits



Oct. 12, 1948. K. P. GROAT 2,451,385

CONTROL OF CONVERTIBLE EVAPORATOR-CONDENSERS FOR USE IN REFRIGERATIVE CIRCUITS Filed July 22, 1946 l2 Bummer Kain; P. Gro a wz n.

attorneys Patented Oct. 12, 1948 CONTROL OF CONVERTIBLE EVAPORA'E'OR- CONDENSERS FOR USE IN REFRIGERA- TIVE CIRCUITS Keith PrGroat, York, Pa., assignor to Yorir Corporation, York, Pa, a corporation of Delaware Application'luiy 22.1946, Serial No. 685,4l36

4 Claims. 3

This invention relates to refrigeration and particularly to means for operating an evaporating coil temporarily as a condenser. This-might be required for various special purposes such as defrosting, but the invention was developed in connection with an air conditioner operating according to the principle disclosed in the patent to Newton 2,195,781, issued April 2, 1940, and will be here describedas so embodied.

According to this embodiment of the invention, the evaporator of a refrigerative conditioner is divided into two sections arranged serially in the path of the air being conditioned. The first section always acts as a refrigerative evaporator to abstract heat from the air and thus cool and dehumidify it. The second section normally acts as a refrigerative evaporator but at times is con verted into a condenser so as to serve as a reheater for the air cooled and dehumidified by the first section.

When temperature or humidity is, or both are. above chosen values the system operates. Ii temperature is above the chosen value both sections operate as evaporators, regardless of the degree of humidity. If temperature is below and humidity is above the chosen value the system operates with the second section functioning as a condenser. Under such conditions the temperature of the first section is somewhat reduced, since the compressor operates at constant speed. if both temperature and humidity fall below the chosen values the system is shut down. A thermostatic limit switch is added to shut the system down if temperature falls below a set limit.

The conditioner about to be described operates on the same basic principle as does the Newton device but makes use of a greatly simplified valve,

mechanism for converting the second evaporator section to a condenser. This change avoids maintenance difiiculties encountered heretofore, reduces the cost of manufacture-simplifies the control, and improves the operating characteristics of the plant, making it commercially practicable for small units which receive little or no maintenance attention. I

An illustrative embodiment of the invention will now be described by reference to the accompanying drawings, in which-- Fig. 1 is a diagram part in section but chiefly in elevation, illustrating the completesystem.

Fig, 2 is an axial sectional view of the differential fiow valve, drawn on a larger scale.

Fig. 3 is an axial sectional view 01' the threeway pressure operated valve or "switch valve iii which determines the function or the second section of the evaporator.

Referring to Fig. l a compressor ii is driven by motor 'l and delivers compressed refrigerant through line 8 to a water-cooled condenser 9. In Fig. 1 line 8 which is commonly called the hot gas line" has several branches each of which is in free communication with the main line. For this reason the numeral is used collectively for the line and branches. A pressure regulated valve ii responsive to pressure in line 8 controls the flow of cooling water to condenser increasing the how of water as head pressure rises and decreasing it as head pressure falls.

Refrigerant liquified in condenser 9 fiows by liquid line it to the thermostatic expansion valve i3 which discharges through distributor M into both sections of the evaporator. The coils i5, i6, ll typify the first section of the evaporator and these are connected by manifold it and suction line it? with the compressor intake. The coils ti and 22 typify the second section of the evaporator, and each is fed. through a corresponding dif= ferential flow valve 23, whose construction is shown in Fig. 2.

As indicated in Fig. 2 the valves 28 may comprise ordinary flap check valves 28 each with a bleed port 26. Any scheme that would permit free flow toward the coils and restrict baclr flow can be substituted.

The coils 2i, at discharge into a manifold con vnection 26 which leads to the side connection of the switch valve indicated in Fig. l by the numeral 2? applied to its body. The construction of the switch valve is shown in Fig. 3.

The body ti and head 28 are connected by sleeve nut 29 and form the valve housing. In the body is a seat bushing ti with ports 82 and M to which the manifold connection 223 leads. The bushing 3i seals on a gasket 34 which projects inward far enough, to ofifer a seat for the rim of the cup-shaped valve 35 when that is forced to the left against the urge of a coil compression spring 36. This spring urges the valve to the right. A port through head 28 is connected by branch 37 with suction line it. A port in the righthand end of body 21 is connected to the high pressure gas line 6 through a normally closed valve 3%. This valve may be opened by energizing solenoid 89. Expansion valve ll has the sual thermostatic bulb it on suction line IS with connecting capillary tube 42. The usual pressure connection appears at 43 and is shown connected to coil 11.

With the compressor running and valve 38 4 closed valve 35 will move to the right exposing The embodiment illustrated is exemplary only ports 32. It need not seal tight, since valve 18 for, as stated, the principles of the invention can prevents-flow through the right end port. Thus e variously applied and can be used for various 28 is connected to the suction line and coils 2i, purposes. 22 operate as evaporators. If valve 38 be 5 What is claimed is: l opened the hot gas will force valve 35 to the left 1'. The combination of a refrigerative circuit inuntil it seals on gasket 84. \This disconnects cluding an evaporator having an inlet for volatile manifold 26 from suction line l9 and admits hot refrigerant and a suction connection; flow congas from line B through ports 33 and manifold trolling means at said inlet adapted to permit 26 to coils 2|. 22. Ports 2!! develop the necessary l0 free flow intothe evaporator and restricted flow in back pressure to cause coils 2|, 22 to operate as the reverse direction :valve means controlling said condensers. Refrigerant condensed therein flows suction connection; yielding means normally through ports 25 to the first evaporator section maintaining said valve means open; a combined 00119 l5. l8, l'l. expansible chamber motor and now controller Observe that parts so far described could be adaptedtoclose said valve means when said motor present in any compressor-condenser-evaporator is subjected to pressure, and so arranged that as circuit having a divided evaporator so that the the motor moves in ,valve closing direction it first conversion scheme is obviously generally availthrottles flow through said valve means and then able for any-use-for example, if coils 2| and 22 op n a passage from the-expanslble chamber were operated at sub-freeflng temperature they 0 motor to the evaporator; a sourceof warm refrig could be defrosted by opening valve as. similarly, rant see underpr s ure; and a valve ont llin by mere duplication. each section of the soap flow therefrom to said motor.

orator could be provided with defrosting means, 2. In a refrigerative circuit, the combination 0! v The finned heat transfer portions of the coils a compressor; a condenser to which the mpr l5. i6, l1, 2| and 22 extend across a duct 44. A 25 sor deliverscompressed refrigerant; exp ns on fan driven by motor to draws air upward valve means fed by the condenserF-an evaporator through the duct 44 from the conditioned space, c mprising at least two c ions f i p l y causes it to flow over the coils, and discharges it the expansion valve me ns, nd e ch avin a back into the conditioned space. Atmospheric connection to the compressor intake; differential conditions could be-sensed in the room but I prefl w m a s tw t pans on valve means fer to locate the controls in the air stream flowing d t least e Section Of the p a o a e toward the coils because this gives a good averrang d to p rmi -f flOW w rd i v p rator, age indication f room conditi n section and to restrict flow in the reverse direc- Switch 46 is an ordinary thermostatic switch 3 tion; a hot gas line lea n from th ompr ssor which is normallyclosed against its contact 61 d e; a three way valve interposed in the and opens to stop the unit if temperature falls connection between saidevaporator section and Labnormally low. It is thus merely a low limit he compressor intake and connected with said switch normally performing no regulatory funchot. as in id v v v n a no m l position tion. witch 48 is the regulatory thermostatic in which it places the evaporator section in comswitch and is a snap acting two contact switch. 40 m o With the compressor ntake and an Ii temperature is below itscontrol point it closes abnormal position in which it interrupts said against ontact 49 If temperatur i above t communication anf connects the hot gas line with e control oint it closes against contact 5|. switch th evap at s n; m ans asin said valv 52 is a humidostatic switch which closes against to said normal position: a pressure motor for contactsitwhn humidity is high. The device 54 opening said v lv p t d bids, Said mot r is a safety pressure switch which opens in response ein Subject to pressure invthe hot gas i n to excess pressure-in line 8. Switch 55 is a dual a valve controlling said hot gas line,

manual switch used to shut down or run fan 45 3. The combination defined in claim 2 in which and to shut down or condition for operation the the differential flow means comprise a freely Op nmain compressor motor. 50 ing one way flow valve. and a "constantly open The electric leads are indicated at Ll, L2 and restr ct d o passage 11 984 8 fi W elation L3 and the lines to motor I at Bl, B2 and B8. The therewith.

against contact, humidostat switch 52 is in constarter switch shown in diagram at 56 has four 4. The combination defined in claim 2 in'which contactors 51, 58, 59 and ii. The first three of the three way valve comprises a body having two these control the motor I while 8! controls the 66 spaced sets of side ports connected with said evapsolenoid 39 by controlling a circuit from Bl orator section, and ports in its opposite ends conthrough solenoid 39 through contactor 8| to u. n ct d resp ti ly wit t compr ss r intake The ccntrolcircuit for the starter is from L3 and with the hot gas connection: a pis n valve through switch 55, pressure switch, 54, limit shiftable in said hous n to e D B S d sets of side switch 46 to switches. and 52 and thence via '60 po ts s l ct v y at opp s t ds f th va v and contact 5| or 53 and the control circuit of the serving at one limit of motion to seal the end port starter 56 to Ll. If switch 48 closes against conwhichleads to the compr o in d sprin tact 5| motor I will run regardless of theposition urging said valve away from the position just of switch 52 but the circuit through solenoid 39 named but with insufllcient force to resist hot is bpen at as so valve at is closed and all coils as p essure r act n on said va veoperate; as evaporators. If switch 48 closes 1 KEITH P. GROAT.

m1. 1: it closes motor runs and solenoid as is REFERENCES CITED.

. energized so that valve 3' open 'and 00118 32 The following references are of record in the operate as refrigerant condensers. 70 m of this patent;

The details of the starter switch! are conventional. The limit switch 40 is provided to shut Um F PATENTS down the system if the temperature a'oes abnor- Number Name Date mally low while the machine operates under the Y 2,141,715 Hilger Dec. 27, 1938 control of humidity switch 52. 2,195,781 Newton Apr, 2, 1940 

